Adding Link widget
Adding directional link widget
Fix whitespace
Updated example notebook
Load link widget javascript
Load the link models
on("destroy",...) -> once("destroy",...) so we don't keep a reference to it, preventing gc

Thanks to Sylvain Corlay for the suggestion.
Allow FileLinks to not recursive into subdirectories
Remove unneeded modules, and added docstring info on recursive parameter
Merge remote-tracking branch 'public-upstream/master' into links-rebase

Conflicts:
	examples/Interactive Widgets/Widget Events.ipynb
gh-7044: set TMPDIR to workingdir in tests
lazy load widgets

Allow warnign to appear in notebook at the time widets get imported
Change exception message
using codemirror mode/meta for detection
removing monkeypatch, importing rest of codemirror default theme
fixing tests
handling explicitly provided modes from kernelspec.language_info
more fidgeting before starting over
checking in css
Merge pull request #6996 from bollwyvl/cm-meta-highlight

Using codemirror mode/meta for mode detection